1. Field of the Invention
The present invention relates to a device and a method for diagnosis of abnormality in a battery pack which comprises a plurality of cells which are connected in series-parallel.
2. Description of the Related Art
With relation to a battery pack in which a plurality of cells are connected in series, there is a per se known type of battery pack abnormality diagnosis device which detects whether any cell is in an abnormal state, based upon the measured value of the voltage of each cell (see Japanese Laid-Open Patent Publication No. 2002-033135).
However, with a battery pack in which a plurality of parallel blocks, each of which is made up from a plurality of cells connected in parallel, are themselves connected in series, it is not easy to measure the cell voltages by providing an individual voltage sensor to each of the cells connected in parallel within each of the parallel blocks, both from the point of view of cost and from that of technique. Accordingly, a method has been considered of measuring the voltage of each parallel block unit by providing one sensor to each such parallel block unit.